Considering the Christian origins of the holiday do Jews celebrate or is it against Jewish law? I assume secular Jews celebrate it for the most part? How about reform Jews?
There’s no Jewish law against celebrating Thanksgiving. Orthodox Jews are free to observe it or not as they see fit.
There is a Jewish law against observing Gentile religious rituals, but the vast majority of Jews would consider Thanksgiving to be an entirely secular affair.
Just don’t expect them to eat the bacon stuffing.
Thanksgiving has a Christian origin? More details, please.
AFAIK, American Jews of all stripes celebrate Thanksgiving.
Thanksgiving is not a Christian holiday, but a secular one.
When the Pilgrims and the Indians had what is considered the first “Thanksgiving” dinner, sure, God was thanked for getting them through to the harvest.
And when George Washington made the first proclamation of a day of Thanksgiving, in 1789, God was mentioned in the proclamation as being deserving of thanks.
But while churches may hold services on Thanksgiving, it’s more like singling out for remembrance a single day, when we should be giving thanks year round. Kind of like Mother’s or Father’s Day.
I’m sure as long as said feast is kosher, sure. And let’s not forget-the Natives were not Christians either.
I celebrate Thanksgiving with my cousins, who are mostly Conservative Jews. There’s nothing religious about it whatsoever.
Same here, with my parents and sister. Turkey = good!
Mrs. Plant became convinced that baby chickens do not nurse their Mothers, so I was able to baste the chicken with butter instead of olive oil.

So would the majority of Christians, I would think. And even for those who see “thanking God” as an essential component, this in no way excludes observant Jews.
Technically, Jewish law allows poultry to be eaten with dairy products. However, Jewish tradition (Tradition! Tra dish un!) is against it.
Back To The OP
I’d say all of the Conservative Jews I know celebrate Thanksgiving.
I was raised in a conservative Jewish household. We always celebrated Thanksgiving (in fact, it’s my favorite holiday). For us it wasn’t about thanking G-d for our feast, but it was a day to be thankful for all that we have.
I am Orthodox. My family has always been fairly neutral about Thanksgiving - if my aunt and uncle invited us, we’d go, and if not, we’d have an ordinary weeknight dinner. As a result, I can take it or leave it, although I find the idea of having a big meat meal right before the Sabbath (when I’m going to have big meat meals for both Friday night and Saturday lunch) rather silly. My husband’s family - traditional but not fully observant parents, very observant Conservative aunt and uncle, fairly secular cousins - is very into it, with my in-laws driving three hours for the annual dinner. The aunt and uncle, who are deeply conservative politically, feel that Thanksgiving is an expression of the fundamental religiosity of America and its founders. This makes me very uncomfortable, since as friedo mentioned, Thanksgiving is only OK for Orthodox Jews (in contrast to Christmas, Halloween, Valentine’s Day, etc.) because it’s considered a totally secular celebration. I also think they’re wrong, FWIW.
There are Orthodox Jews who are of the mindset that anything that smacks of non-Jewish traditions is to be avoided, who might eat turkey any other night of the year but that one, although I don’t personally definitely know any. Generally, the closer to ultra-Orthodox that one gets on the spectrum of Orthodox Judaism (very, very long post not really suited to here), the less likely people are to care about Thanksgiving, although there are certain exceptions who tend to be very into a meal celebrating the idea of giving thanks to America for being good to Jews.
Thanksgiving (like Christmas) is a popular time for weddings among American Orthodox Jews, because everybody’s off work, and the majority of the guests aren’t expected to be so invested in Thanksgiving dinner that they would skip a wedding.
That’s what I thought too, isn’t it a celebration of “hey, we’ve been here for a year and didn’t die out”?
That’s completely civilian.
My rabbi taught that the Pilgrims were inspired by the Jewish fall harvest festival of Sukkot.
They’ve swiped other things from us, what the heck. 
I’m Orthodox, and I’ve had turkey and the whole works on Thanksgiving since I got married. My parents were never into it, but my in-laws are (my mother-in-law grew up conservative and became Orthodox in college, which might have something to do with it), and I have no problem with it.